Abstract

The well known method of equal channel angular pressing (ECAP), used for batch production of ultrafine grained (UFG) bulk metals, suffers from low productivity which is related to substantial loses of material in a multi-pass process and a low value of plastic strain cumulated in a single pass. In this paper a case study concerning ECAP was presented to show how International Cold Forming Group (ICFG) guidelines for cold forming can address development of industry viable severe plastic deformation (SPD) technology. Based on these recommendations a multi-turn ECAP process was proposed to increase the efficiency and minimize the cost. The production procedure was optimised experimentally using a tool set for small cross-section billets. The results obtained for ECAP of aluminium billets are shown for the classical one-turn channel and the proposed twoturn channel. The whole process chain which enables production of UFG metals using only 4 passes is described. It comprises the main ECAP operation and auxiliary procedures, e.g. lubrication suitable for the aluminium billets. The results of metallurgical testing are presented to confirm the process ability to refine grain structure. Finally, the design of a scaled-up ECAP rig, capable of processing 26x26mm2 cross-section billets, is presented, together with the ECAP experimental results and extensive force analysis.